As methods for storing heat, sensible heat storage utilizing the temperature change (for example, Patent Literature 1: Japanese Patent Laid-Open No. 6-50681) and latent heat storage utilizing the phase change of substances (for example, Patent Literature 2: Japanese Patent Laid-Open No. 10-238979) are known.
Among these, the sensible heat storage technology, since whereas being capable of store heat in high temperatures, the technology utilizes only sensible heat by temperature changes of substances, has a problem that the heat storage density is low. A technology proposed as a method of solving such a problem is a latent heat storage technology of utilizing latent heat of molten salts and the like and storing heat.
Various forms of heat storage bodies have been proposed as heat storage bodies to be used in the latent heat storage technology; and for example, Patent Literature 3 (Japanese Patent Laid-Open No. 11-23172) discloses inventions of a latent heat storage capsule characterized in that metal films of one layer, two layers or three layers are formed on the surface of a latent heat storage material, a producing method of a latent heat storage capsule characterized in that a latent heat storage material is coated with a metal film by an electro-plating method, and the like.
Further Patent Literature 4 (Japanese Patent Laid-Open No. 2012-140600) discloses an invention of a heat storage microcapsule in which a core containing at least one water-soluble latent heat storage material selected from salt hydrates and sugar alcohols, and a polymer obtained from a water-soluble monomer mixture of a water-soluble monofunctional monomer and a water-soluble polyfunctional monomer is coated with a shell formed of a hydrophobic resin.
Further Patent Literature 5 (Japanese Patent Laid-Open No. 2012-111825) discloses an invention of a heat storage body having: an internal heat storage body composed of a substance having heat storageability; and an outer shell composed of a ceramic including the internal heat storage body and having a relative density of 75% or higher.